Apparatus and method for communicating digital information on AC power lines
First Claim
1. A method for obtaining a logic signal from a first signal conducted by an AC power line to effect digital communication, said first signal including a first signal component having a first frequency for a first duration, said first signal component representing a first digital logic state, said first signal also including an impulse noise component and an outband signal component having a second frequency substantially different than said first frequency, said method comprising the steps of:
- (a) coupling said first signal to an inductive component of a first tuned circuit, said first tuned circuit having a resonant frequency that is substantially equal to said first frequency, said impulse noise component including a relatively large inband noise component having a frequency that is approximately equal to said first frequency, said first signal component and/or said inband noise component causing said first tuned circuit to oscillate at its resonant frequency;
(b) rapidly damping the oscillations of said first tuned circuit by means of a resistive element in said first tuned circuit immediately after the duration of said first signal component and/or of said inband noise component to rapidly reduce any continuing oscillation of said first tuned circuit immediately after the end of the duration of said inband noise component;
(c) filtering said first signal by means of a second tuned circuit that is substantially more selective than said first tuned circuit in order to further substantially attenuate any outband components of said first signal, said second tuned circuit having a resonant frequency that is substantially equal to said first frequency, said first signal emerging from said second tuned circuit with said first signal component and/or said inband noise signal therein, any previous outband components of said first signal having been substantially attenuated by said first and second tuned circuits; and
(d) producing a first logic signal level representing said first logic state if said first signal contains any AC components that have a duration as long as said first duration.
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Accused Products
Abstract
A carrier current transceiver includes a transmitter section and a receiver section coupled to an AC power line. In the transmit mode, input data in the form of a logical "0" enables a carrier frequency signal to excite a tuned cavity. The tuned circuit includes a first winding of transformer, a capacitor and a damping resistor. A second winding of the transformer is capacitively coupled to the AC power line to produce a stepped down carrier current signal to represent a transmitted logical "0". A logical "1" is represented by absence of the carrier current signal. In the receive mode, a small carrier current signal representing a logical "0" is received via the AC line and is stepped up by the transformer and capacitively coupled to an input of the receiver section. Outband frequencies are removed by means of a second tuned circuit and the resulting signal is amplified by self-biased CMOS inverter circuitry and then is limited by a diode limiter circuit before being input to a phase locked loop data recovery circuit that produces a logical "0" if the carrier frequency is applied for a predetermined period. The damping resistor critically damps large oscillations produced in the first tuned circuit by large noise impulses on the AC line to prevent such oscillations from enduring long enough to be detected as logical "0"s by the phase locked loop data recovery circuit.
85 Citations
23 Claims
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1. A method for obtaining a logic signal from a first signal conducted by an AC power line to effect digital communication, said first signal including a first signal component having a first frequency for a first duration, said first signal component representing a first digital logic state, said first signal also including an impulse noise component and an outband signal component having a second frequency substantially different than said first frequency, said method comprising the steps of:
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(a) coupling said first signal to an inductive component of a first tuned circuit, said first tuned circuit having a resonant frequency that is substantially equal to said first frequency, said impulse noise component including a relatively large inband noise component having a frequency that is approximately equal to said first frequency, said first signal component and/or said inband noise component causing said first tuned circuit to oscillate at its resonant frequency; (b) rapidly damping the oscillations of said first tuned circuit by means of a resistive element in said first tuned circuit immediately after the duration of said first signal component and/or of said inband noise component to rapidly reduce any continuing oscillation of said first tuned circuit immediately after the end of the duration of said inband noise component; (c) filtering said first signal by means of a second tuned circuit that is substantially more selective than said first tuned circuit in order to further substantially attenuate any outband components of said first signal, said second tuned circuit having a resonant frequency that is substantially equal to said first frequency, said first signal emerging from said second tuned circuit with said first signal component and/or said inband noise signal therein, any previous outband components of said first signal having been substantially attenuated by said first and second tuned circuits; and (d) producing a first logic signal level representing said first logic state if said first signal contains any AC components that have a duration as long as said first duration. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12)
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13. A carrier current transceiver system comprising in combination:
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(a) a transmitter; (b) a receiver, said receiver including (i) a first tuned circuit which has a first frequency as its resonant frequency; (ii) means responsive to a first signal, which is conducted by an AC power conductor and includes an Ac signal component that has a frequency equal to said first frequency, for coupling said first tuned circuit to said AC power conductor and causing said first tuned circuit to oscillate at said first frequency in response to said AC signal component, said first signal also sometimes including impulse noise containing an inband impulse noise component having said first frequency, said inband impulse noise component also causing said first tuned circuit to oscillate at said first frequency; (iii) resistive damping means in said first tuned circuit for immediately and rapidly damping oscillations that continue in said first tuned circuit after the end of the duration of said inband impulse noise component, thereby preventing continued oscillation of said first tuned circuit from effectively extending the duration of said inband impulse noise component of said first signal as said first signal passes through said first tuned circuit; (iv) a second tuned circuit which has a resonant frequency equal to said first frequency and has a substantially narrower pass band and a substantially higher Q than said first tuned circuit, said second tuned circuit receiving said first signal and substantially further attenuating any outband components that may be in said first signal; and (v) means responsive to said second tuned circuit for detecting said AC signal component in said first signal after said first signal has passed through said second tuned circuit, said detecting means producing a logic level representing a first logic state if said AC signal component has a duration that exceeds a predetermined maximum expected duration of any inband impulse noise component likely to be conducted by said AC power conductor. - View Dependent Claims (14, 15, 16, 17, 18, 19, 20, 21, 22)
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23. A method for obtaining a logic signal from a first signal conducted by a conductor to effect digital communication, said first signal including a first signal component having a first frequency for a first duration, said first signal component representing a first digital logic state, a noise signal having an inband component and an outband component being superimposed on said conductor, first signal also including an impulse noise component, said outband signal component having a second frequency substantially different than said first frequency, said method comprising the steps of:
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(a) coupling said first signal to a first tuned circuit, said first tuned circuit having a resonant frequency that is substantially equal to said first frequency, said large inband noise component being relatively large and having a frequency that is approximately equal to said first frequency, said first signal component and/or said inband noise component causing said first tuned circuit to oscillate at its resonant frequency; (b) rapidly damping the oscillations of said first tuned circuit by means of a resistive element in said first tuned circuit immediately after the duration of said first signal component and/or said inband component to rapidly reduce any continuing oscillation of said first tuned circuit immediately after the end of the duration of said inband noise component; (c) producing a first logic signal level representing said first logic state if said first signal contains any AC components that have a duration as long as said first duration; and (d) filtering said first signal by means of a second tuned circuit that is substantially more selective than said first tuned circuit in order to further substantially attenuate said outband component and/or andy outband components of said first signal before step (c), said second tuned circuit having a resonant frequency that is substantially equal to said first frequency, said first signal emerging from said second tuned circuit with essentially only said first signal component and/or said inband noise signal therein.
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Specification